1. Field of the Invention
The present invention relates generally to the field of mufflers for engines in oilfield applications. More specifically, the present invention discloses a muffler for engines in oilfield applications that employs a fine mist of well water to reduce noise, remove pollutants from the exhaust gases, and vaporize a large portion of the well water to reduce the volume of well water to be transported off-site.
2. Statement of the Problem
Many oil and gas wells produce significant quantities of water, as well as oil or gas. In many cases, this water cannot simply be discharged due to its salt content or other pollutants. The conventional approach to this problem has been to haul this well water away by truck for off-site treatment or disposal. The well operator is typically charged based on the volume of well water that must be transported. These fees can be very substantial. Therefore, well operators have a significant interest in reducing the volume of well water to be hauled away.
The prior art in this field includes U.S. Pat. No. 4,804,477 (Allen et al.), U.S. Pat. No. 4,882,009 (Santoleri et al.) and U.S. Pat. No. 7,201,225 (Smith et al.), and U.S. Patent Application Pub. No. 2004/10261952 (Hart et al.) that show examples of evaporators for reducing the volume of well water using heat sources other than the well engine.
A separate, but related problem involves the noise and air pollution produced by engines used to power oil and gas wells. These are typically large, stationary internal combustion engines. Similar engines are also used at compressor stations used for collecting and transporting gas and oil through pipelines to market. Also, engines are used in oilfield applications for driving electrical generators to produce electrical power used by other equipment close to oil and gas wells (e.g., water pumps at an injection well). Although many engines in oilfield applications are located far from human habitation, others are close enough to dwellings or environmentally-sensitive areas to be of concern. In any event, applicable governmental laws or regulations may limit noise and air pollution from such engines. Therefore, a need exists for a muffler to effectively limit noise and air pollution from engines used in oilfield applications.
The prior art in this field includes U.S. Pat. Nos. 4,995,460 and 5,335,728 (Strahan). The Strahan '728 patent discloses a system for evaporating water at gas wells. The Strahan system is powered by heat from a compressor engine, but employs a separate muffler and heating vessel. The Strahan '460 patent is a variation on the system disclosed in the Strahan '728 patent. Hot exhaust gases from the compressor engine pass initially through a pipe running through an evaporator, and then enter a separate muffler. A portion of the exhaust gases from the muffler can be recirculated by a pipe to make a second pass through the evaporator to help vent steam from the evaporator. Here again, the muffler and evaporator are separate.
The prior art also includes a wide range of conventional mufflers for internal combustion engines that reduce noise by means of acoustic baffles or sound-dampening techniques.
Finally, the prior art includes U.S. Pat. No. 4,647,394 (Wetch et al.) and U.S. Pat. No. 3,853,484 (Sudar et al.), which disclose devices for use with combustion engines that combine the functions of a muffler and scrubber. Exhaust gases pass through a venturi which aspirates a reactant material into the exhaust gas stream near the venturi throat.